The sysfs battery change broke GetBrightness on dell latitude computers. The issue is there since ubuntu using this change, http://gitweb.freedesktop.org/?p=hal.git;a=commitdiff;h=4541abd23fd02118a1a7f8b825aed338d2a5d638 on 0.5.10, the current git version has the same bug $ dbus-send --system --print-reply --dest=org.freedesktop.Hal `hal-find-by-capability --capability laptop_panel` org.freedesktop.Hal.Device.LaptopPanel.GetBrightness Error org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken. when running this command the hald log gets the error "[20311]: 23:39:42.424 [D] addon-dell-backlight.cpp:231: Received GetBrightness DBUS call process 20311: arguments to dbus_message_get_args() were incorrect, assertion "(error) == NULL || !dbus_error_is_set ((error))" failed in file dbus-message.c line 1667. This is normally a bug in some application using the D-Bus library." Reverting the change $ dbus-send --system --print-reply --dest=org.freedesktop.Hal `hal-find-by-capability --capability laptop_panel` org.freedesktop.Hal.Device.LaptopPanel.GetBrightness method return sender=:1.100 -> dest=:1.107 reply_serial=2 int32 6 and the hald log has "[20436]: 23:41:43.964 [D] addon-dell-backlight.cpp:231: Received GetBrightness DBUS call [20436]: 23:41:43.968 [D] addon-dell-backlight.cpp:82: Reading 6 from the AC backlight register"
Thanks to Sjoerd Simons who figured the issue addon-dell-backlight.cpp filter_function() is using AC = libhal_device_get_property_bool (halctx, "/org/freedesktop/Hal/devices/acpi_AC", "ac_adapter.present", &err); or since the sysfs changes there is no "ac_adapter.present" key there and the same err variable is used when calling dbus_message_get_args later
see patch here: http://thread.gmane.org/gmane.comp.freedesktop.hal/10866
*** Bug 14792 has been marked as a duplicate of this bug. ***
fixed: http://lists.freedesktop.org/archives/hal-commit/2008-March/004228.html
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